Figure 4. The number of retinal pigment epithelium (RPE) cells that had entered the cell cycle 72 h after lesioning were not directly associated with the lesion site. A: Schematic representation of lesion configurations and demarcation of center from periphery on an RPE tissue sheet. B: Total cell numbers were counted in central and peripheral areas, both in terms of those directly associated with a lesion and those distant from lesions. Different combinations of lesions were applied. First, no lesion (control), which represents Ki67 numbers in normal RPE. Second, cell numbers found after one central lesion. Third, cell number after one peripheral lesion. Finally numbers following after one central (c) and one peripheral (p) lesion, and finally numbers following two central and two peripheral lesions. Irrespective of the lesion configuration, elevation in Ki67 positive cell number was always greater was always greater in the periphery, even when only one central lesion was made. While Ki67 numbers increased with lesion number, the number of Ki67 expressing cells found following two lesions in each area was not greater than when one lesion was made in each area. The progressive elevation in cell numbers was statistically significant between no lesions and 1c+1p lesion (see the text for statistical significance).